Document 1ypX0QovOOVp7r1wrepXQvrmX

I> /if' ; rI VI; l $ ??' t - :4` * 4 ;! `<ii>' .1. .v. .1. AKCIIIII-S or INDUSTHIAI. HliAl.ru /.f.vt; r.-i.wi-.H. I.imiting the investigation to cases coming lie found in another group of the same size, discussions widt to autopsy, as has bcvii frequently dune iu but representative of the general population. of the asbestos earlier studies, still further restricts its use .It is true that investigation of cases fmm with clinicians, p in generalization. The problem with which such a sample can furnish information ol City ami l*r<. we are mtieerncd is whether asU-stus valuable for research, hut the use of this and of the V'.ni.. miners cxjicrience more lung, cancer than information in drawing generalizations is other interested j docs the general imputation. Tlie answer necessarily restricted. It is the obligation morbidity data, a! necessitates the collection of reliable infor of both the investigator and of those who were available fr mation on aslicstos miners as a group, as read his rvpirt to make projicr comparisons hospitals iu Mon: well as on the general imputation. ami to draw only those conclusions which the 13 cancer detv It seems advisable to discuss the differ arc valid and justified. A good statistical ences between the epidemiological approach study of cases of cancer of the lung occur and that used in the studies which have ring in a group of auto|>sie$ can lead to a been reported to date. A wry iui|mrt.-iut proper inference cmircniing the frequency consideration is the fad dial lung eanevr, of lung rauccr aim mg cases coming to in spite of its increasing numbers, is still a autopsy, but only to such cases. For in- disease of low incidence: that is. in a given formation from such a study to be pm. imputation not many persons will contract jccied to some larger group, it is nccessarv this particular disease. This fact requires that the autopsies represent a goad sample that large samples or groups must Ik* stud of that larger group. To assume that such ied tu provide iiieniilngful results. ls: ihe case ill any particular series is dan Recognizing the difficulty of obtaining gerous and likely to be false. such large samples, most earlier writers There is some danger that the figures deviated from the epidemiological method re]Kirtcd by some authors may be miscon and sought to circumvent the requirement strued as .-qiptyiiig to aslwstos workers nr of observing well |ktsoiis by (1) conqiar- even asIxTSlos miners, when; in fact, tlK. ing the relative frequency of cancer in vnri- authors in question do not make this gen- ous -sites: C2) conqKiriug the rotative realization. nor can the generalization |n. frequency of cancer in a group of hospital made for lliv reasons stated. Close study of ized patients: f3> comparing; the relative the reports rewals that the percentages frequency of cancer in a group of cases cited relate only to the group ot autopsies coming to autopsy. covered by the particular investigation. Attempting to compare tu-o |H>ptibtiim groups, looking only :!i the rebtive fre quency of cancer in various (sidy sites, may result in finding a higher |>crcctitagc ' (relative frequency) iu one of the groups, when, in fact, the mortality rate of cancer of a particular organ is exactly the same in both groups. This is very clearly dem onstrated in the excellent article by bom.1" The present study, in contrast to ihc earlier works, has been planned to utilize die epidemiological method. A well-defined group of asbestos millers lias licen estab lished in such a way that it constitutes a good sample of the whole population of asbestos miners in Quctxv. Data for all members of this group have been collected and analyzed. Those concerning lung can incc. However. I, edily in lung ca: in depend upon These we found vital statistics lc^ of Ilealth_jii-i>uv: liminary survey, it ;ive and delude.' iatlwred with res employed in the : anti the mortalily population. Following this initial effort was < if data relating i been processed tit: ford Mines since i -imilar infnnitali..: jt AsIk-sIos. One. rccorils included I. sonal metlical hi: numiier of years i. ol Weighted expo. the initividuar.s he: ,)f his death. From this infor to formulate a "eoh defined, should be whole group, anil c lefinite jwriod fit li: experience indicates The mortality rate from a pirtionlar cause Is the true measure of comparison. ft is appireut that selected groups such as hospitalize:! patients or autopsy cases may lint be iu any way representative of cer have received most careful considera tion. Details of die mvdiods employed will Ik*- set forth later, hut the ly(>c of approach is considered to jivnnit of fair comparisons and valid gvtiernliuitions. of aslicslnsis in less pnsurv imtst lie so ingly. the cohort w: every miner who h. live or more years, a larger group, and Ilint iu dealing with < Collection and Analysis of Data employment rolls in such samplvs. the observer may easily find A preliminary survey of {mtcntinl sources' nones |mscd personn mure cases of a given disease than would of information in Felirieiry, 1956, involved of employment. we MS I'ol. 17. Junr. It/\l Jnitui--Truan r~ ' rv i._."*.i!|ufi, S.V-'J" JW ?r